Photonics Dictionary

A device designed to measure crystal properties by analysis of crystal diffraction.

A CubeSat is a type of miniaturized satellite characterized by its standardized size and modular design. CubeSats are typically used for scientific research, technology demonstration, educational...

A sudden, brief increase in current or voltage in a circuit that can damage sensitive components and instruments. Preventive measures include slow-starter circuits, filtering and static control.

The measure of departure from a flat surface, as applied to lenses; the reciprocal of radius. Applies to any surface, including lenses, mirrors and image surfaces.

Custom lapping and polishing services involve specialized processes used to improve the surface finish and dimensional accuracy of components to meet specific requirements or standards. These...

A technique for measuring fiber attenuation or distortion by performing two transmission measurements. One is at the output end of the full length of the fiber. The other is within 1 to 3 m of the...

An instrument designed to measure the proportion of light emitted by a source in the blue region of the spectrum.

An organizational method used in optical design computer programs. The technique produces one number (merit function) to measure the state of correction of an optical system. This number, which is...

A multidimensional array of values that is commonly used in programming to describe a time series of image data. Each dimension in the data cube represents a new attribute, while the cells of the...

A device used in ultrasonic imaging to measure the velocity and attenuation of compressional waves in a transparent liquid by virtue of acoustic waves set up in the liquid. The wavefronts serve as a...

A chart, either printed on paper or prepared photographically on glass plates or film, that consists of 3-bar resolution test objects, sine-wave test objects for modulation transfer function...

For an optical table, the amount of displacement that occurs when a heavy load is placed or moved on the surface. To measure deflection under static load, a 113-kg (250 lb) weight is placed in the...

A quantitative measurement of the coherence of a light source; equal to the visibility (V) of the fringes of a two-beam interference test: where Imax equals the intensity at a maximum of the...

1. An instrument used to measure the opacity or density of dyes, pigments or dispersed particles that form an image in or on a medium, such as a photographic film. 2. A device used to measure the...

The square of the ratio of the measured detectivity to the theoretical maximum detectivity.

A measure of the sensitivity of a detector; the reciprocal of noise equivalent power (NEP). See D*.

1. A device designed to convert the energy of incident radiation into another form for the determination of the presence of the radiation. The device may function by electrical, photographic or...

A detector array refers to a collection of individual detector elements arranged in a two-dimensional grid or matrix format. Each element within the array is capable of detecting electromagnetic...

A detector-Dewar assembly typically refers to a combination of a detector and a Dewar flask used in scientific instruments, particularly in the field of infrared spectroscopy or other applications...

A lidar (light detection and ranging) technique used in pollution monitoring. Two light beams are emitted simultaneously, one at a wavelength that will be absorbed by the target particles, and the...

A device that produces an interferogram that can be directly related to the temperature gradient and thereby provides a direct measure of the convective heat transfer coefficients.

The measurement of the spectrum bands formed by a spectroscopic sample, based on the differences between the sample and the reference cell it is placed in.

Diffraction efficiency is a measure of how effectively a diffractive optical element (DOE) or diffraction grating directs light into specific diffraction orders or achieves a desired optical effect....

A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel grooves or rulings. These rulings act as an array of closely spaced slits...

A measurement device used to study the structure of matter using the diffraction of electromagnetic radiation.

Diffuse reflectance spectroscopy (DRS) is a nondestructive analytical technique used to investigate the optical properties of materials, particularly in the field of spectroscopy. Unlike traditional...

An instrument used to measure expansion of solids, liquids and gases.

A scale located on the eyepiece focusing screw and used to measure the amount of defocusing of the eyepiece in diopters. The reciprocal of the image distance in meters is a measure of the amount of...

A unit of optical measurement that expresses the refractive power of a lens or prism. In a lens or lens system, it is the reciprocal of the focal length in meters. For example, if a lens has a focal...

A telescopic system having an eyepiece, a reticle and an objective. The instrument measures wavefront power in diopters.

A device that provides simple and reliable laser power and energy measurement. Essentially a heat flux sensor producing an output proportional to the power, rather than the energy input.

A measure of the dispersive properties of a glass. The relative dispersion is defined as: where C, D, and F refer to the material's index of refraction at the three chief Fraunhofer lines in the...

A distributed feedback laser (DFB laser) is a type of semiconductor laser diode designed to emit coherent, narrow-bandwidth light with precise control over the wavelength. It achieves this through a...

A spectroscope having a divided circle and a means for the rapid reversal of prisms for the measurement of refractive index of the prism for a specific wavelength.

A spectrophotometer that measures the amount of ozone in the atmosphere through a comparison of solar energy at two wavelengths in the ozone's absorption band. This comparison is achieved by...

A device used to detect and measure the quantity of exposure to nuclear or x-ray radiation, and dependent on the fact that such radiation ionizes a gas.

A measurement of the spatial resolution of a line or area array in an optical character recognition scanning device.

Measurement derived from calculation when incident flux of a negative is entirely diffuse and all radiation transmissions are included.

Interferometric measurement of the interference pattern recorded when a complex object is illuminated by two laser pulses that interfere and form the pattern to be evaluated.

Intensity distribution in the image of an edge. The gradient of the edge-response curve is a measure of the image quality of the optical system under test.

The maximum variation in thickness of a lens as measured around a diameter centered on the optical axis. The ETD divided by that diameter yields the wedge of the lens.

A scale attached to a microscope eyepiece that is seen superimposed on the image and that is used to measure the dimensions of the viewed object.